Table 1.
Descriptive statistics per sample
| n | Mean (SD) | % of sample | n | Mean (SD) | % of sample | ||
|---|---|---|---|---|---|---|---|
| Mandatory sample (Twente) | Voluntary sample (IJsselland) | ||||||
| Age | 8761 | 14.23 (1.14) | - | Age | 1571 | 14.29 (1.07) | - |
| Educationa | 9295 | - | 51.5 | Educationa | 1723 | - | 61.3 |
| Genderb | 9359 | - | 49.2 | Genderb | 1952 | - | 55.8 |
| School experiencesc | 9354 | 2.52 (.85) | - | School experiencesc | 1913 | 2.13 (.73) | - |
| Subjective healthd | 9356 | 1.85 (.70) | - | Subjective healthd | 1892 | 1.75 (.69) | - |
| SDQ | 9349 | - | - | SDQ | 1952 | - | - |
| Unlikely | 8275 | - | 88.5 | Unlikely | 1712 | - | 91.3 |
| Possible | 753 | - | 8.1 | Possible | 104 | - | 5.5 |
| Probable | 321 | - | 3.4 | Probable | 60 | - | 3.2 |
| Tobacco consumptione | 9291 | - | 9.13 | Tobacco consumptione | 1951 | - | 3.5 |
| Alcohol consumptionf | 9015 | - | 51.8 | Alcohol consumptionf | 1944 | - | 26.2 |
| Lifetime alcohol consumptiong | 9280 | 5.67 (5.26) | - | Lifetime alcohol consumptiong | 1684 | 2.31 (3.48) | - |
| Alcohol in past four weeksh | 9272 | - | 41.5 | Alcohol in past four weeksh | 1678 | - | 11.1 |
| Sexual intercoursei | 9247 | 1.28 (.79) | - | Sexual intercoursei | 1649 | 1.13 (.55) | - |
aPercentage students HAVO/VWO
bPercentage females
c(1) great fun, (2) fun, (3) neutral, (4) not fun, (5) dreadful
d(1) very good, (2) good, (3) neutral, (4) not good, (5) poor
ePercentage daily smoker
fPercentage respondents who had ever consumed alcohol
g0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11–19, 20 > times
hPercentage respondents who drank alcohol in the past four weeks
i(1) never, (2) once, (3) couple of times, (4) regularly